Starting from version 2.4 of wxWidgets, there are several ways to use a wxScrolledWindow. In particular, there are now three ways to set the size of the scrolling area:
Note: if Maximum size hints are still supported by SetVirtualSizeHints, use them at your own dire risk. They may or may not have been removed for 2.4, but it really only makes sense to set minimum size hints here. We should probably replace set_virtual_size_hints with set_min_virtual_size or similar and remove it entirely in future.
As with all windows, an application can draw onto a wxScrolledWindow using a device context.
If you don't wish to calculate your own scrolling, you must call prepare_dc when not drawing from within OnDraw, to set the device origin for the device context according to the current scroll position.
A wxScrolledWindow will normally scroll itself and therefore its child windows as well. It might however be desired to scroll a different window than itself: e.g. when designing a spreadsheet, you will normally only have to scroll the (usually white) cell area, whereas the (usually grey) label area will scroll very differently. For this special purpose, you can call set_target_window which means that pressing the scrollbars will scroll a different window.
Note that the underlying system knows nothing about scrolling coordinates, so that all system functions (mouse events, expose events, refresh calls etc) as well as the position of subwindows are relative to the "physical" origin of the scrolled window. If the user insert a child window at position (10,10) and scrolls the window down 100 pixels (moving the child window out of the visible area), the child window will report a position of (10,-90).
Returns: Sequence: {xx, yy}
Translates the logical coordinates to the device ones. For example, if a window is scrolled 10 pixels to the bottom, the device coordinates of the origin are (0, 0) (as always), but the logical coordinates are (0, 10) and so the call to calc_scrolled_position(0, 10) will return 0 in yy.
Returns: {xx, yy}
Translates the device coordinates to the logical ones. For example, if a window is scrolled 10 pixels to the bottom, the device coordinates of the origin are (0, 0) (as always), but the logical coordinates are (0, 10) and so the call to CalcUnscrolledPosition(0, 0, &xx, &yy) will return 10 in yy.
Enable or disable physical scrolling in the given direction. Physical scrolling is the physical transfer of bits up or down the screen when a scroll event occurs. If the application scrolls by a variable amount (e.g. if there are different font sizes) then physical scrolling will not work, and you should switch it off. Note that you will have to reposition child windows yourself, if physical scrolling is disabled.
Parameters
Remarks
Physical scrolling may not be available on all platforms. Where it is available, it is enabled by default.
Similar to fit_window, but sizes the interior (virtual) size of a window. Mainly useful with scrolled windows to reset scrollbars after sizing changes that do not trigger a size event, and/or scrolled windows without an interior sizer. This function similarly won't do anything if there are no subwindows.
Get the number of pixels per scroll unit (line), in each direction, as set by set_scrollbars. A value of zero indicates no scrolling in that direction.
Returns: {x, y}
Get the position at which the visible portion of the window starts.
Remarks
If either of the scrollbars is not at the home position, x and/or y will be greater than zero. Combined with get_client_size, the application can use this function to efficiently redraw only the visible portion of the window. The positions are in logical scroll units, not pixels, so to convert to pixels you will have to multiply by the number of pixels per scroll increment.
Gets the size in device units of the scrollable window area (as opposed to the client size, which is the area of the window currently visible).
Motif only: true if the window has a backing bitmap.
Call this function to prepare the device context for drawing a scrolled image. It sets the device origin according to the current scroll position.
If you wish to implement OnPaint yourself, you must call this function yourself. For example:
procedure onPaint( atom this, atom event_type, atom id, atom event )
atom dc
sequence size
dc = create( wxPaintDC, {this} )
prepare_dc( this, dc )
size = get_dc_size( dc )
set_pen( dc, wxBLACK_PEN )
draw_line( dc, {0, 0} & size )
delete_instance( dc )
end procedure
Scrolls a window so the view start is at the given point.
Parameters
Sets up vertical and/or horizontal scrollbars.
Parameters
Remarks
The first pair of parameters give the number of pixels per 'scroll step', i.e. amount moved when the up or down scroll arrows are pressed. The second pair gives the length of scrollbar in scroll steps, which sets the size of the virtual window.
xPos and yPos optionally specify a position to scroll to immediately.
For example, the following gives a window horizontal and vertical scrollbars with 20 pixels per scroll step, and a size of 50 steps (1000 pixels) in each direction.
set_scrollbars( window, 20, 20, 50, 50, 0, 0, 0 );
wxScrolledWindow manages the page size itself, using the current client window size as the page size.
Note that for more sophisticated scrolling applications, for example where scroll steps may be variable according to the position in the document, it will be necessary to derive a new class from wxWindow, overriding OnSize and adjusting the scrollbars appropriately.
Set the horizontal and vertical scrolling increment only. See the pixelsPerUnit parameter in set_scrollbars.
Call this function to tell wxScrolledWindow to perform the actual scrolling on a different window (and not on itself).
Sets the virtual size of the window in pixels.